3.9 GHz, 3rd Harmonic 4-Cavity Module Status H Edwards/E Harms Fermilab
Outline 3.9GHz Module • What is it and what will it do? – It is not in SRF B&R category (B&R 15.02.011 General Acc Dev) • Why do it & What has it done for Fermilab? • Progress, Accomplishments, History – Technical progress • The steps: Design, Fabrication, Process, Vertical test, Dress, Horizontal test, Module assembly, Infrastructure – Associated systems - LLRF • Lessons Learned and Problems encountered • Schedule - Looking Forward • Collaboration - Future Collaboration? • Future at Fermilab? • Conclusion May 18-19, 2009 DOE SRF Review 2
The 3.9 cavity module -What is it -what will it do? The 3.9 cavity module -What is it -what will it do? • The 3.9 GHz module, ACC39, will be installed in the DESY FLASH injector just after the 1.3GHz ACC1 (first) cryo module. • It will be used in conjuction with this module in order linearize the bunch energy vs. time over the bunch length. • This in turn should make “bunch compression” to very short bunches with high peak currents more efficient, or a more controlled longer bunch charge distribution. • The SASE FEL operation should become more efficient and stable seeded operation (sFlash) possible. • This is an important proof of principle not only for FLASH and XFEL but also for accelerator-photon physics, and a learning experience. • The control of the phase and amplitude of the 1.3-3.9 module pair will be difficult and very important. May 18-19, 2009 DOE SRF Review 3
Bunch Compression with 3.9 GHz Module After acceleration w/o After compression w/o Short bunch Flat bunch ~250 fs σ From M Dohlus With 3rd harmonic From P Piot et al May 18-19, 2009 DOE SRF Review 4
Why Do It & What Has It Done for Fermilab? • The 3.9 effort is part of a collaboration with DESY. • In this collaboration DESY has advised Fermilab on many of the aspects of SRF development and has supplied design and assembly information. • DESY provided for Fermilab a 8 cavity module at 1.3 GHz. This Module is being installed in the NML facility. • The 3.9 GHz module has been/will be a learning experience for FNAL in all aspects of beta 1 SRF cavity and module design through commissioning. • Successful completion will clearly show Fermilab’s growing competence and abilities in SRF technology. • It is important that we learn and benefit for our experiences and “Lessons Learned” . May 18-19, 2009 DOE SRF Review 5
3.9GHz Overview Photos 3.9GHz Overview Photos May 18-19, 2009 DOE SRF Review 6
Infrastructure for 3.9 Infrastructure for 3.9 • Some old and some new – Old - A0 SRF R&D Infrastructure – Modest, built up over the years • Soft wall clean room • UV water & Ultrasonic bath • High Pressure Rinse sufficient for small cavities • Vertical test (short dewar) • Cryo - dewar fed and recovered to CHL • RF systems (1.3 & 3.9) – New - set up and used for 1.3 GHz • Horizontal Test Stand (HTS) at Meson (MDB) • String and Coldmass assembly at MP9 • Module assembly at Industrial Center (ICB) – Some steps very time inefficient • Welding at Sciaky (or JLab) and weld preparations • Chemistry at ANL (conflict with their work) May 18-19, 2009 DOE SRF Review 7
Cavity Fabrication Steps Cavity Fabrication Steps • Documents on Cavity and Helium Vessel Fabrication and Welding by M. Foley, et al – 3.9 GHz Cavity Fabrication Specification • Material • Blanks for half cells • Fabrication of Components • End Assemblies • Welding of Cavity • Final Test of Cavity – Procedures for Welding Helium Vessels to 3.9 GHz Cavities • Preparation for Electron Beam welding • Electron Beam Welding • Preparation for TIG Welding • Final TIG welding • E-beam Weld Parameters • TIG Weld Parameters May 18-19, 2009 DOE SRF Review 8
Fabrication and Processing Steps • Table of processing steps by A. Rowe – About 200 steps after fabrication • Outline – Preliminary Processing Sequence • Preliminary Preparation • External Surface Preparation • Internal Bulk Surface Preparation • Hydrogen Degasification • RF tuning – Vertical Test Processing Sequence • Internal Surface Preparation • 1st Vertical Test • 2nd Vertical Test – Titanium Helium Vessel Welding – Horizontal Test Processing Cycle May 18-19, 2009 DOE SRF Review 9
String and Module Assembly Steps • Assembly Travelers by T. Arkin, M. McGee, D. Olis, et al – Assembly QA Traveler – Cavity String Assembly – Cold Mass Assembly Parts 1-3 – Final Assembly Traveler – Shipping Document – Warm Coupler Assembly Document May 18-19, 2009 DOE SRF Review 10
Warm/Low power RF Measurements T. Khabiboulline modes May 18-19, 2009 DOE SRF Review 11
Summary of Last Vertical Tests - Design 14MV/m Summary of Last Vertical Tests - Design 14MV/m with and w/o HOM antennae with and w/o HOM antennae 1.8K 2.0K • C3 (2008_07_22 with HOM ant) – Q @14 MV/m 2.2e9 – Max Gradient 17.6 MV/m, Q 1.2e9 • C3 (2008_08_27 no HOM ant) • C3 (2008-08_27 no HOM ant) – Q @14 MV/m 5.2e9 – Q@14MV/m 2.6e9 – Max Gradient 22.8 MV/m, Q 1.3e9 – Max Gradient 20.3 MV/m, Q 1.7e9 • C5 (2007_08_22 no HOM ant) – Q @14 MV/m 5.1e9 – Max Gradient 25 MV/m, Q 2.0e9 • C5 (2008_10_04 with HOM ant) – Q @14 MV/m 4.1e9 – Max Gradient 17 MV/m, Q 3.7e9 • C7 (2008_02_07 no HOM ant) – Q @14 MV/m 2.3e9 – Max Gradient 25.1 MV/m, Q 1.3e9 • C7 (2008_10_27 with HOM ant) • C8 (2007_11_08 no HOM ant) – Q @14 MV/m 2.0e9 – Q @14 MV/m 4.9e9 – Max Gradient 24.8 MV/m, Q 1.2e9 – Max Gradient 24.2 MV/m, Q 1.5e9 • C8 (2008_12_03 with HOM ant) – Q @14 MV/m 2.8e9 – Max Gradient 20.4 MV/m, Q 1.3e9 May 18-19, 2009 DOE SRF Review 12
3.9 GHz Cavity Vertical Tests - 1 May 18-19, 2009 DOE SRF Review 13
3.9 GHz Cavity Vertical Tests - 2 May 18-19, 2009 DOE SRF Review 14
Cav 3,5,7,8 Horizontal Test Results at HTS F3A3 22.5 MV/m F3A5 22.5 MV/m Design Gradient 14MV/m F3A7 26.3 MV/m F3A8 24 MV/m May 18-19, 2009 DOE SRF Review 15
3.9 Schedule Highlights - 3.9 Schedule Highlights - past ast • 2002 TESLA Facility Phase 2 Report with 3.9 GHz module for bunch compression (TESLA-FEL 2002-01) • 2002-3 Cavity design documents (TESLA-FEL 2002-05, 2003-01/FNAL TM 2210) • 2005 DESY-FNAL MOU on 3.9 module • 2006, 03-06 C1,C2 failures, Multipacting & HOM wall thickness • 2006, 08 F3A3 fabrication finished- first usable cavity • 2007, 05 F3A3 good vertical test after HOM formteils cut, 24MV/m • 2007, 10 F3A5 vertical tests with HOM feed-throughs complete 19MV/m • 2008, 02-09 F3A5 in horizontal test stand (HTS) • 2008, 04 F3A5 achieved 22.5MV/m in HTS • 2008, 12 F3A7 last cavity of four removed from HTS • 2009, 01 String assembled in MP9 Clean Room • 2009, 02 Cold mass to ICB • 2009, 04 Module finished and shipped to DESY 2002 to 2009 - start to ship - for module tests at DESY May 18-19, 2009 DOE SRF Review 16
Problems & Lessons Learned - 1 • Technical issues – HOM design and multipacting - 1-post redesign for F3A7, F3A8 – HOM antennae feedthroughs - followed JLab type design – Titanium Helium vessel weld design, welding and Titanium pipe welding – Design mistakes - e.g. thickness of HOM can top • Infrastructure issues – e- Beam welder availability – BCP etch availability, FNAL & ANL – HTS commissioning – Maintenance of effective CR, HPR, and Cryo systems at A0 • Procedural issues – Pressure vessel testing and Engineering note, ORC May 18-19, 2009 DOE SRF Review 17
Problems & Lessons Learned - 2 • Major delays (~3 months or more) – Understanding and Redesign of HOM antennae • Re-prototyping of the e- beam welding parameters for HOMs (DESY). – Redesign and rebuilding of the Ti Helium vessels • Certification of the welds and welding procedures. – E beam welding done at Sciaky, typically 1 day a week to 1 day/2 weeks. Not always available, others scheduled • Preparation for remote welding cumbersome and time consuming. • Sciaky sold machine making ~6 month delay as new machine installed and new parameters determined. – BCP infrastructure availability • FNAL - only minimal availability for etch of edges of half cells, etc prior to welding. ~ 5 month delay while facility was improved and recertified. • ANL - ANL collaboration very important. Used their existing G150 system, but not always available. May 18-19, 2009 DOE SRF Review 18
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